logd: record and replay log messages

To profile different log buffer types and configuration, this change
adds the ability to record log messages and adds a tool that will
replay those log messages through different log buffer implementations
and collect stats about the execution.

Test: log messages replay correctly
Change-Id: I0dc6c545b782fa7732e325dde109c496b137d0dd
diff --git a/logd/RecordedLogMessage.h b/logd/RecordedLogMessage.h
new file mode 100644
index 0000000..f18c422
--- /dev/null
+++ b/logd/RecordedLogMessage.h
@@ -0,0 +1,30 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <inttypes.h>
+
+#include <log/log_time.h>
+
+struct __attribute__((packed)) RecordedLogMessage {
+    uint32_t uid;
+    uint32_t pid;
+    uint32_t tid;
+    log_time realtime;
+    uint16_t msg_len;
+    uint8_t log_id;
+};